The invention relates to an automatic handling apparatus for plate-shaped objects.
An apparatus of this kind is known from DE-PS No. 3,219,502. A number of wafers of the same size and shape are located in the magazine. The wafer sizes are standardized, with the result that a small number of magazine types is sufficient. Insofar as wafers have to be handled automatically during the production process, it is always a question of a relatively large number of objects of the same kind. It thus makes economic sense to use specific exchangeable types of magazines which can be introduced in the loaded condition into air-conditioned chambers and ultraclean rooms, e.g., via locks.
For the examinations of samples it is necessary to have freely selectable access to the wafers. This is achieved by a special design of the gripping arm on the manipulator. Since the wafers are relatively light, a vacuum pick-up has become established for the gripping arm. The linearly movable manipulator having a gripping arm forms a functional unit.
The masks used for the exposure operations are of decisive importance in the production of the patterns on the wafers. Extreme requirements are imposed on the dimensional accuracy and intactness of the mask fields. As a rule, stable, and hence, relatively heavy glass plates produced from a glass having a very small coefficient of expansion are used as mask carriers. Each mask carrier is stored and transported in a special cassette. The mask carrier is removed from this cassette manually when required and placed at the location of use. Because of the sensitivity of the mask fields, the mask may only be gripped in the edge region.
The increasing fineness of semiconductor patterns makes even greater demands on the equipment for measuring and checking the patterns. The most modern mask measuring machine achieves a measuring accuracy in the nanometer range. In this measurement range even slight temperature gradients by reason of manual contact with the heat of the body lead to measurement errors. Since the measuring machines are set up in an air-conditioned chamber. A certain period of time must first of all be spent waiting for the mask carriers which have been introduced to achieve temperature equalization before measuring is begun.
An acceleration of this procedure is conceivable if loading is carried out using appropriately temperature-regulated gripping tools. In each case, the loading of the measuring machine requires the presence of an operator, since to date there is still a relatively large variety of types of mask carriers, making individual handling of each individual disk necessary. Different measuring times for the individual samples furthermore make necessary additional attentiveness on the part of the operative.